@33export,
One thing is the assertion that Constantine and successors "made Christianity law," which is a muddled one at best, another thing is that the story, or more precisely stories, of Jesus predate the First Council of Nicaea.
One of the earliest stories of Jesus is the
Gospel of Mark which, it is generally agreed, was written around 70 AD.
What the First Council of Nicaea did, among other things, was to attempt to reach a consensus about different aspects of Christian theology, like the relationship between Christ and God the Father, the calculation for the date of Easter, and the beginnings of the Church's ecclesiastical law.